// This function will work hide all div's of class hide_class and show the div with id show_div
// additionally, if there is a show_div_nav element, the class will be set to 'current'
function rollTab(show_div, hide_class){
  // Don't do anything unless the show_div is hidden
  if (!$(show_div).visible()){
    // Select all the divs of class hide_class
    $$('.' + hide_class).each(function(div){ 
      // Hide the div
      if (div.visible()) Effect.toggle(div.id, 'appear', {duration: 0.25}) //div.toggle('appear',{ duration: 0.25 }); 
      // Remove current style from the classes from the nav
      $(div.id + '_nav').removeClassName('current') 
    });
    //show the show_div
    Effect.toggle(show_div, 'appear', { duration: 0.25, delay: 0.225 })//                    $(show_div).toggle('appear', { duration: 0.25, delay: 0.2 });
    if (div = $(show_div + '_nav')) div.addClassName('current')
  }
}